Device and method for staged implantation of a graft for vascular repair
A graft for repairing defects in arteries is formed from a flexible graft and at least one attachment system. A device and method is disclosed for implanting a graft within the vasculature of a patient, in which the graft is inserted into the patient at a different stage than the attachment systems, and which allows for direct percutaneous insertion of the graft and attachment systems. The method permits control over the position of the graft in the vasculature during the course of deployment of the graft and attachment systems by providing for traction forces to be applied to opposing ends of the graft.
This application is based on U.S. Provisional Application No. 60/157,985 filed Oct. 6, 1999.
FIELD OF THE INVENTIONThe present invention relates to intraluminal grafts and their attachment systems which are used for repairing defects in vessels and other lumens within the body. More particularly, the present invention relates to systems for forming linear and bifurcated grafts and to methods for delivering such grafts and their attachment systems to the correct position within the defective body lumen by staged implantation.
BACKGROUND OF THE INVENTIONAneurysms are discrete dilations of the arterial wall. One of the most common, and among the most life threatening, is an aneurysm of the abdominal aorta between the renal and iliac arteries. If untreated, the aneurysm dilates progressively with an ever increasing risk of rupture and hemorrhagic death.
One method of treatment is provided by direct surgical intervention, in which the defective vessel may be bypassed or replaced using a prosthetic device such as a synthetic graft. The risks involved in direct surgical intervention of this magnitude are great, and include an extensive recovery period.
In recent years a less invasive method of treatment has evolved through a series of inventions. The details vary, but, conventionally, a resilient tubular conduit (herein referred to as a “graft”) is introduced into the defective vessel by means of catheters introduced into the femoral artery, and is attached to the non-dilated arteries above and below the aneurysm using expandable metallic or plastic cylinders (herein referred to as “attachment systems”).
However, the use of generally cylindrical grafts to reinforce vascular walls in a patient is not without problems. The known methods for delivering grafts to the required location within a patient's vascular system conventionally require that an attachment system be delivered simultaneously with the graft, axially overlapping the graft and located either on the interior or the exterior of the graft's lumen, so that upon deployment of the graft the attachment system is expanded to attach the graft to the vascular wall. In the prior art, the attachment system is typically connected to the graft before implantation in the patient by means such as stitching. Because grafts are conventionally required to be compressed into a capsule or sheath before being implanted in final position within the patient's vascular system, delivery capsules or sheaths must be sufficiently small to enable insertion into the patient's vessel, and, once inserted, must be sufficiently flexible to allow bending around corners and branches of the patient's vascular tree. Yet, as a consequence of the practice of delivering the attachment system simultaneously with and axially overlapping the graft, the outer diameter of the delivery capsule or sheath containing the compressed graft in such cases is increased by the presence of the compressed attachment system.
One of the problems encountered in the art of delivering grafts to the vascular system of a patient is that complications may be encountered in maneuvering the compressed graft and its delivery system around the bends and branches of the patient's vascular system. It will be appreciated that the greater the outer dimension of the capsule containing the compressed graft to be delivered, the more inflexible it will be, making delivery to the final destination more difficult and perhaps even impossible in some patients.
Another problem encountered in the art of graft delivery is that, in the majority of cases, the patient must be subject to surgery in which the appropriate vessel is surgically exposed and opened by incision to allow entry of the graft. Significantly, it is this surgical procedure on the vessel which gives rise to the most serious complications known in the art of minimally invasive graft delivery, with complications taking the form of infection, patient discomfort, and necrosis of the vessel itself. However, if the outside dimension of the delivery capsule were sufficiently small, it might be possible, depending on the size and condition of the patient, to insert the capsule into the patient's vessel by applying sufficient force to the skin and artery of the patient with a sharpened end of the graft's delivery capsule, similar to the commonly known method of inserting a needle directly into the vein or artery of a patient.
There therefore exists a need to reduce the outside dimension of the capsule or sheath containing a compressed graft to be delivered to the patient's vascular system. This invention addresses these needs.
SUMMARY OF THE INVENTIONThe present invention provides a device and a method for delivering a graft to a desired location within a patient's vascular system, and then, while maintaining the graft's position by applying traction forces to the ends of the graft, to deliver at least one attachment system for attaching the graft to the vascular wall. By delivering the graft and the attachment system in separate stages, the outside dimensions of the delivery capsules or sheaths containing the graft and the attachment system separately may be substantially less than that of a capsule or sheath containing the graft and the attachment system together. This reduction in outside dimension of the delivery capsule or sheath facilitates delivery of the graft and may allow for the direct percutaneous insertion of the graft and its attachment system, depending on the condition of the patient.
One aspect of the present invention provides a device and a method for repairing a linear vascular structure. A method in accordance with this aspect of the present invention includes the use of a linear graft compressible between an uncompressed condition and a compressed condition, a guide-wire, an upstream traction catheter and a downstream traction catheter, and at least one attachment system compressible radially between an expanded condition and a compressed condition. The guidewire may be placed to run between a first access point in the vascular structure located superior to the defective portion of the vessel to be repaired, and a second access point located inferior to the defective portion of the vessel. By using the traction catheters releasably connected to the graft, the graft in a compressed condition is fed over the guidewire to a desired position within the vascular structure, whereupon the graft is released from its compressed condition to revert toward its uncompressed condition. While maintaining the graft in a desired position by applying traction forces through the traction catheters to both ends of the graft, at least one attachment system in compressed condition is fed over the guidewire to a desired position within the graft, whereupon the attachment system is expanded to its expanded condition. In the preferred embodiment, all elements of the repair are introduced into the vascular system by direct percutaneous insertion. When the required number of attachment systems have been inserted and expanded within the graft, the traction catheters are released from the graft and are withdrawn from the vascular system together with the guidewire, leaving the graft attached to the vascular wall.
Another aspect of the present invention provides a device and a method for repairing, by direct percutaneous delivery of the graft and attachment system, a bifurcated vascular structure having an aortic branch and left and right iliac branches projecting from the aortic branch at a point of bifurcation. A method in accordance with this aspect of the present invention includes the use of a bifurcated graft foldable between an uncompressed condition and a compressed condition and having a superior trunk and left and right inferior legs or leg portions projecting from the superior trunk at a point of bifurcation, a first and a second guidewire, an upstream traction catheter, a left downstream and a right downstream traction catheter, and at least one attachment system, compressible radially between an expanded condition and a compressed condition. The first guidewire is configured to run between a first access point superior to the aortic branch of the vascular structure and a second access point inferior to one of the iliac branches of the vascular structure. The second guide wire is configured to run between the second access point and a third access point inferior to the other iliac branch of the vascular structure. By using the upstream traction catheter releasably connected to the graft, the graft in a compressed condition is fed over the first guidewire to a desired position within the vascular structure. By using the left and right downstream traction catheters releasably connected to the left and right inferior legs of the graft respectively, the left and right inferior legs of the graft may be pulled into the left and right iliac branches of the vascular structure. Once located at the desired position within the vascular system, the graft may be released from its compressed condition. While maintaining the graft in its desired position by applying appropriate tension to at least one traction catheter, at least one attachment system in compressed condition may be fed over one of the guidewires to a desired position within the graft, whereupon the attachment system may be expanded or allowed to expand. When the required number of attachment systems have been inserted and expanded within the graft, the traction catheters are released from the graft and are withdrawn from the vascular system together with the guidewires, leaving the bifurcated graft attached to the vascular wall. In the preferred embodiment, all elements of the repair are introduced into the vascular system by direct percutaneous insertion.
By allowing the graft to be delivered at a different stage than the attachment system (or attachment systems), the diameter of the capsule or sheath delivering the graft may be reduced. Furthermore, it will be appreciated that, because the graft of the present invention may be pulled, rather than pushed, into position, the delivery capsule does not suffer adversely from the reduced resistance to kinking which otherwise follows from its reduced diameter. On the contrary, the reduction in diameter of the delivery capsule, combined with its placement by a traction force, allows greater flexibility which has the advantage of facilitating delivery of the graft through the branches of the vascular system. It also has the advantage, in suitable cases, of permitting delivery of the graft by a direct percutaneous insertion, without the need for a further surgical procedure to provide access into the vascular system of the patient. If such a surgical procedure can be avoided, it may be possible to use the procedure of minimally invasive luminal repair in a wider range of situations by a wider range of medical personnel. For example, it may be used as an outpatient procedure in which the patient is not hospitalized. It will be appreciated that outpatient treatment in this context will be considerably less costly than inpatient treatment to achieve the same result, and will be substantially more convenient for the patient.
Other features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention.
The device and method disclosed by the present invention may be used to deliver to a patient's vascular system a flexible tubular graft which may be straight, tapered, or bifurcated. In the preferred embodiment of this invention, the graft may be delivered to the patient's vascular system without performing surgery on the patient to open the vessel prior to insertion of the graft; rather, insertion is achieved percutaneously over a guidewire using the Saldinger technique or with a small diameter introducer sheath. Alternatively, insertion is achieved by applying force to the skin and vessel of the patient with the tapered end of the repair assembly sufficient to gain direct entry into the vessel. This method of insertion is referred to herein as the “direct percutaneous” method of insertion.
The terms “superior” and “inferior” shall be used herein to have the same meaning as the terms “up” and “down” respectively and shall signify ends or directions which are towards and away from the patient's head, respectively. The terms “right” and “left” shall be used herein to signify ends or directions which are toward the patient's right and left sides, respectively. It should be noted that in the anatomical drawings provided herein, the patient faces the reader.
As exemplified in
As exemplified in
Grafts are preferably formed from a biocompatible material having sufficient strength to withstand the implantation procedure described herein, and to endure the biomechanical forces that will be imposed on the graft. Such materials may include polyester materials such as DACRON, polytetrafluoroethylene, polyester materials, and silicone. Grafts are preferably made from material formed into woven fabric. The inferior end of the upstream traction catheter is releasably connected to the superior end of the graft. The superior end of the downstream traction catheter is releasably connected to the inferior end of the graft. There are numerous releasable connections known in the art.
The repair assembly 46 shown in
The upstream traction catheter 48 is then moved in a superior direction over the guidewire 30, eventually exiting through the first access point 36. This movement may be achieved by pushing the upstream traction catheter over the guide wire from the second access point 38 into the vascular system of the patient, until it protrudes from the first access point 36. Alternatively, as exemplified in
The position of the repair assembly 46 and graft 60 within the vascular system may be ascertained by using flouroscopic methods that are known in the art. For example, a radio-opaque marker 78 may be attached to the inferior end of the sheath 74, as exemplified in FIG. 4. The marker may take the form of an annular ring formed from a metal, such as stainless steel or platinum-iridium, or may consist of any radio-opaque material. Once located in the desired position, the sheath is withdrawn by sliding it superiorly, over the upstream traction catheter and over the graft, thereby releasing the graft from its compressed condition and allowing it to revert to its uncompressed condition, as exemplified in FIG. 5. The graft may contain further radio markers to facilitate its final positioning.
Next, one or more attachment systems, compressible radially between a compressed condition and an uncompressed condition, are introduced into the bore of the uncompressed graft in order to engage the graft with the vascular wall. There are many types of attachment systems, or anchors, known in the art that will achieve the result of fixing the graft to the vascular wall. Such attachment systems may be self-expanding, may be manufactured from shape memory alloy such as Nitinol, and may include hooks or barbs. Alternatively, the attachment systems or anchors may be expandable by a balloon catheter.
As exemplified in
During insertion of the attachment system into the bore of the graft, the graft may be held in a fixed position by applying the appropriate tension forces to the two traction catheters 48, 54. When the delivery assembly 80 is being pushed over the guidewire 30, the sheath and the pushrod are connected to each other to prevent relative axial movement between the attachment system and the sheath, thereby avoiding premature expansion of the attachment system. The position of the attachment system in relation to the vascular structure may be determined by using flouroscopic methods such as those described above in relation to positioning the graft. When the attachment system has reached the desired position, the sheath is withdrawn by sliding it inferiorly over the pushrod while holding the pushrod in place. As exemplified in
In one embodiment of a self expanding attachment system suitable for use with the present invention, an attachment system may be used which is made from a piece of wire which is bent in a generally undulating form and configured to have a generally cylindrical profile. This embodiment of self-expanding attachment system 76 is exemplified in a deployed state in
In another embodiment, an attachment system 92 suitable for using with the present invention, exemplified in
It will be appreciated by one of skill in the art that, in the configurations of these previously described two embodiments, when the attachment system is compressed, its legs and apices are urged radially outward in a direction generally at right angles to its axis. Preferably, the self-expanding attachment systems of both described embodiments are made from a material having highly elastic properties such as nickel-titanium alloys, including Nitinol, since the same allows a great amount of expansion and compression of structures without permanent deformation. Implantable stainless steel is also known to be satisfactory for the purpose. An additional material from which such attachment system may be manufactured is Elgiloy™ which is a chromium-cobalt-nickel alloy manufactured and sold by Elgiloy of Elgin, Ill.
It will be appreciated that, as long as the guidewire 30 protrudes from the second access point 38 and runs within the bore of the uncompressed graft 60, and the traction catheters 48, 54 remain releasably connected to the graft, a plurality of attachment systems may be sequentially inserted within the bore of the uncompressed graft in the manner described above.
Once the required number of attachment systems have been deployed within the graft, the traction catheters are released from their connection to the graft and are removed together with the guidewire, leaving the graft fixedly supported by the attachment systems within the vascular system.
Although the description of the aspect of the present invention set forth above relates to the staged implantation of a tubular or tapered graft, another aspect of the invention includes a device and method for the staged implantation of a bifurcated graft into a bifurcated vascular structure. As exemplified in
Then, as exemplified in
It is desired that the left downstream traction catheter 122 and the second guidewire 100 be configured to enter the second access point 38′, as exemplified in
Before introducing the graft into the vascular system, the graft is enclosed in a sheath 74′, which extends superiorly to slidably surround the upstream traction catheter 48′, as exemplified in FIG. 11. As in the case of the sheath 74 used to deliver the straight or tapered graft, the sheath 74′ used to deliver a bifurcated graft may have a varying diameter, and may be constructed from the same materials.
Having thus fully assembled the repair assembly 46′, the upstream traction catheter 48′, surrounded by the sheath 74′, is then introduced into the vascular system at the second access point 38′ until it protrudes from the first access point 36′. This result may be achieved in the same manner used to introduce the upstream catheter 48 in the case of the straight or tapered graft, that is, either by threading the upstream traction catheter upwards over the first guidewire or by passing a collection catheter downwards over the first guidewire, and releasably connecting the upstream catheter to the collection catheter before withdrawing the collection catheter upwards until the upstream traction catheter emerges from the first access point.
As exemplified in
Once the bifurcated graft is located in a desired position within the aorta, the sheath 74′ may be slidably removed by withdrawing it superiorly over the upstream traction catheter 48′, allowing the graft to revert to its uncompressed condition, as exemplified in FIG. 14. Then, following a technique similar to that disclosed in the case of the straight or tapered graft above, at least one attachment system compressible radially between a compressed condition and an uncompressed condition is provided, and is fed into the vascular system in a compressed condition over the first or the second guidewire within a delivery assembly which includes a sheath or jacket to confine the attachment system in a compressed condition. Using the same flouroscopic technique as disclosed above, the attachment system is located at a desired position within the bore of the graft, and is then expanded or allowed to expand by removing the sheath. As exemplified in
It will be apparent from the foregoing that, while particular forms of the invention have been illustrated and described, various modifications can be made without departing from the spirit and scope of the invention. For example, at the stage when an attachment system is fed into the vascular system over a guidewire, it is not essential to the invention that the guidewire protrude from the access point opposite to the access point into which the attachment system is fed. What is essential is that the guidewire should run into the bore of the graft through the appropriate inferior leg 114 or 118 (in the case of the bifurcated graft), and should extend upward into the bore of the graft as far as is necessary to implant the attachment system within the graft. For instance, the second-guide wire 100 may be repositioned by withdrawing it leftwards until its right end 102 is positioned in the left inferior leg 118 of the bifurcated graft, and by then pushing the guidewire upwards until its right end is positioned within the graft's superior trunk 110, or beyond. Such repositioning may assist in placing attachment systems within the left inferior branch of the bifurcated graft. Moreover, it is not essential to the invention that the graft be introduced through the second access point, but may equally be introduced through the third access point if the necessary changes are made to the points of entry/exit of the guidewires and traction catheters. Furthermore, while the preferred embodiment described above is used to implant a graft in the aorta, alternative embodiments may be used to implant a graft in any lumen of the body.
Furthermore, instead of using self-expanding attachment systems, balloon expanded attachment systems may be used.
Accordingly, it is not intended that the invention be limited, except as by the appended claims.
Claims
1. A method for the percutaneous insertion of a graft having a bore and being supported by at least one attachment system within the vascular system of a patient, the graft capable of assuming a compressed condition and an uncompressed condition, and the at least one attachment system being compressible and expandable radially between an expanded and compressed condition, the method comprising:
- inserting the graft into the vascular system by direct percutaneous insertion;
- applying a traction force to opposing ends of the graft to control the position of the graft within the vasculature, wherein the traction force is carried out using a plurality of catheters, each catheter configured to exert a force on the graft from a different point outside the vasculature;
- positioning the graft adjacent a diseased portion of the vascular system;
- subsequently inserting at least one attachment system into the graft in compressed condition by direct percutaneous insertion into a point of access to the vascular system over a propositioned guidewire;
- positioning the at least one attachment system within the bore of the graft; and
- activating the at least one attachment system from its compressed condition to its expanded condition;
- wherein the attachment system is implanted in the graft to form a seal between the graft and the vascular wall.
2. The method of claim 1, wherein the inserting step includes:
- inserting the graft in compressed condition by direct percutaneous insertion into a point of access to the vascular system over a prepositioned guidewire; and
- activating the graft from its compressed condition to its uncompressed condition.
3. The method of claim 2, wherein the graft is configured to have a bifurcated profile having a superior trunk with a superior end and first and second inferior legs each with an inferior end, and wherein a first catheter having a first end and a second end is releasably connected by the first end to the superior end of the graft and configured so that the second end thereof extends through a point of access to the vasculature in the left axillary artery, a second catheter having a first end and a second end is releasably connected by the first end to the inferior end of the first leg and configured so that the second end thereof extends through a point of access to the vasculature in a first iliac artery, and a third catheter having a first and second end is releasably connected by the first end to the inferior end of the second leg and configured so that the second end thereof extends through a point of access to the vasculature in a second iliac artery.
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Type: Grant
Filed: Oct 6, 2000
Date of Patent: Feb 1, 2005
Inventor: Timothy A. M. Chuter (Atherton, CA)
Primary Examiner: David J. Isabella
Assistant Examiner: Urmi Chattopadhyay
Attorney: William G. Lane
Application Number: 09/684,008
